Fluid pressure producing device



Se t. 10, 1 H. c. BOWEN FLUID PRESSURE PRODUCING DEVICE Filed Sept.- 20, 193 7 INVENTOR. Cffiawi/v ATTORNEYS.

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Patented Sept. 10, 1940 UNITED STATES PATENT OFFICE FLUID PRESSURE PRODUCING DEVICE Herbert G. Bowen, Detroit, Mich., assignor to Hydraulic Brake Company, Detroit, Mich., a corporation of California Application September 20, 1937, Serial No. 164,637

6 Claims. (01. 60-54.6)

s vent o re ates to flu d pressu e braking ative to actuate the shoes into engagement with systems and more particularly to fluid pressure the drum against the resistance of the retractile producing devices for such systems. spring.

An object of the invention is to provide a fluid A piston 44 reciprocable in the cylinder is repressure system including a fluid pressure protained against displacement by a washer 46 seat- 5 ducing device operative to overcharge the system ed onan annular shoulder in the open end of so that the fluid in the system may be maintained the cylinder and held in place by a retaining under a predetermined pressure. ring 48 fitted in a circumferential groove in the Another object of the invention is to provide wall of the cylinder. The washer has an axial 10 a fluid pressure braking system including a fluid bore, and formed on the perimeter defining the 10 pressure producing device operative to maintain bore is a flange 58 providing a suitable bearing the system free from air or gas bubbles. for the piston. The piston has a solid body por- Other objects and advantages of the invention tion 52 slidable through the washer 46, and a cowill appear from the following description, taken extensive cylindrical portion 54 providing a chamin connection with the drawing forming a part ber 56 receiving the extension 28 on the head 26 15 of this specification, and in which: of the cylinder and an annular head. A radial Fig. 1 is a schematic view of a fluid pressure flange 58 on the cylindrical portion 54 of the pisbraking system embodying the invention; and ton divides the annular space between the wall Fig. 2 is a vertical sectional View of the fluid of the cylinder, the extension on the head of the pressure producing device. cylinder, and the piston, into two annular cham- 20 Referring to the drawing, 18 represents a fluid bers 68 and 62 communicating respectively with reservoir having a filling opening l2, normally the reservoir by way of the ports 28 and 22, and closed as by a plug l4, having openings [6 for aplurality of spaced passages 64 through the head venting the reservoir to the atmosphere. Formed 58 provide communications between the chamat the base of the reservoir is a cylinder [8 havbers 68 and 62. A sealing cup 66 seated on the 25 ing spaced ports 28 and 22 providing communi- 4 washer 46 in the open end of the cylinder incations between the cylinder and the reservoir. hibits seepage of fluid from the cylinder, and a The port 28 is controlled as by a check valve 24 collapsible sealing cup 68 seated on the head 58 inhibiting the flow of fluid from the reservoir to controls the passages 64 through the head, and a- 30 the cylinder and yet providing for a restricted spring 10 interposed between the cups 66 and 68 30 flow of fluid from the cylinder to the reservoir, serves to retain the cups against displacement. the restriction being proportionate to a prede- The chamber 56, provided by the cylindrical termined load on the valve. The cylinder has portion of the piston, has in its bottom a plurality one of its ends open and its other end closed as of spaced passages I2 providing communications by a head 26 having a concentric extension 28 between the chamber 56 and the annular champrojecting axially within the cylinder, and the her 60, and arranged in the wall of the chamber head and extension are axially bored to provide 56 adjacent its free end is a port 14, also provida discharge port 38 for the cylinder. ing a communication between the chamber 56 A fluid pressure delivery pipe or conduit 32 and the annular chamber 60. A collapsible seal- 40 connected to the discharge port 38 has branches ing cup 16 seated at the bottom of the chamber 40 connected respectively to fluid pressure actuated 56 controls the passages 12, and a sealing cup 18 motors 34 for the actuation 'of brakes of a 1110- on the extension 28 seals the chamber 56, and a tor vehicle. Preferably the brakes are arranged spring .88 interposed between the cups I6 and 18 in pairs, one pair associated with the front wheels serves to retain the cups against displacement of the vehicle and another pair associated with and also to return the piston to its retracted 45 the rear wheels of the vehicle. position where it is cushioned on the spring 10 The brakes may be of conventional type, each between the sealing cups 66 and 68. including a fixed support or backing plate 36, a The piston has suitably secured thereto a flexrotatable drum 38 associated with the backing ible boot 82 embracing the open end of the cylinplate, a pair of corresponding interchangeable der for the exclusion of dust and other foreign 50 friction elements or shoes 48 pivoted on the backsubstances, and arranged in the back of the ing plate, a retractile spring 42 connecting the piston is a recess 84 for the reception of one end shoes, and a fluid pressure actuated motor correof a thrust rod 86. The other end of this thrust spondlng to the motors 34 mounted on the backrod is pivotally connected to a foot pedal lever ing plate and connected to the shoes and oper- 88 pivotally mounted on a fixed support 90 and 5 normally held against a stop 92 by a retractile spring-94 connecting the lever to a fixed support 96.

In a normal operation, upon depressing the foot pedal lever, force is transmitted therefrom through the thrust rod 86 to the Piston 44, resulting in moving the piston on itscompression stroke. During the initial movement of the piston on its compression stroke, the sealing cup 18 covers the port 14 in the chamber 56, and thereafter, as the piston advances on its compression stroke, fluid is displaced from the chamber 56 through the discharge port 36 and the fluid pressure delivery pipe 32 and its respective branches into the fluid pressure actuated motors, causing actuation of the motors, with the resultant movement of the shoes into engagement with the drums against the resistance of the retractile springs.

As the piston moves on its compression stroke, the capacity of the chamber 60 increases proportionately to the movement of the piston, and this increase in capacity results in the induction of fluid into the chamber 60 from the chamber 62 and passages 64 in the head 58, past the cup 68 into the chamber 60, completely filling the chamber, and during this period of the operation fluid is expelled from the chamber 62 through the port 22 into the reservoir.

Under this condition, upon the conclusion of a braking operation, the operator releases the applied force on the foot pedal lever 88, whereupon the lever is moved under the influence of the spring 94 to its retracted position against the stop 92, and, as the lever moves to its retracted position, the thrust rod 86 connected to the lever is likewise retracted. This results in release of the piston 44 and movement thereof to its retracted position under the influence of the return spring 86.

As the piston moves to its retracted position, fluid is drawn from the reservoir through the port 22 into the chamber 62, and the fluid in the chamber 60 is displaced therefrom under pressure commensurate with the load on the spring 80 through the ports 72, past the cup 16, into the chamber 56. During this movement, fluid is also returning to the chamber 56 from the fluid pressure actuated motors 34, and conduits connecting these motors to the chamber 56, under the influence of the retractile springs connecting the shoes 40 of the respective brake structures. Under this condition the quantity of fluid received by the chamber 56 is in excess of the quantity necessary to completely fill the chamber, and the excess fluid is returned to the reservoir by way of the port 14, the annular chamber 66, and the check valve 24, and, since the valve 24 is loaded to open at a predetermined pressure, it is clear that pressure on the fluid in the system may be maintained at all times.

Although this invention has been described in connection with certain specific embodiments, the principles involved are susceptible of numerous other applications that will readily occur to persons skilled in the art. The invention is, therefore, to be limited only by the scope of the appended claims.

Having thus described the various features of the invention, what I claim as new and desire to secure by Letters Patent is:

1. A fluid pressure producing device comprise ing a cylinder, a piston reciprocable therein, a source of fluid supply for said cylinder, a chamber in the piston, a variable chamber between the piston and cylinder and varying in volume with movement of the piston, means for discharging fluid from the chamber during the compression stroke of the piston, means for inducting fluid into the variable chamber during the compression stroke of the piston, and means for displacing fluid from the variable chamber into the chamber during the retraction stroke of the piston.

2. A fluid pressure producing device comprising a reservoir, a cylinder supplied therefrom, a head on the cylinder having an extension protruding into the cylinder, said head and extension having a bore providing a discharge port, a piston reciprocable in the cylinder having a chamber tween the cylinder and the extension, valve means between said cylinder and reservoir controlling flow therebetween, and valve means between said cylinder and chamber permitting flow from said receiving the extension, :1 head on the piston becylinder into said chamber during the returnstroke of said piston.

3. A fluid pressure producing device comprising a reservoir, a cylinder supplied therefrom, valve means controlling communication between said reservoir and cylinder, a retaining ring in one end of the cylinder, a head on the other end of the cylinder having a concentric extension projecting into the cylinder, said head and extension having a bore providing a discharge port for the cylinder, a piston reciprocable in the retaining ring having a chamber receiving the extension on the head of the cylinder, a. head on the piston slidable between the cylinder and the extension to create pressure in said cylinder during the return stroke of said piston, and valve means permitting flow from said cylinder to said chamber during return stroke of said piston.

4. A fluid pressure producing device comprising a reservoir, a cylinder supplied therefrom, a retaining ring in one end of'the cylinder, a head on the other end of the cylinder having a concentric extension protruding into the cylinder, said head and extension having a bore therethrough providing a discharge port for the cylinder, a piston reciprocable in the retaining ring, a chamber in the piston receiving the extension on the head of the cylinder, said chamber having ports providing communications between the chamber and the cylinder, means for closing said ports during the compression stroke of the piston, an annular head on the piston slidable between the cylinder and the extension on the head, said annular head having passages therethrough, and a collapsible sealing cup closing the passages during the return stroke of the piston.

5. A fluid pressure producing device comprising a reservoir, 9, cylinder supplied therefrom, a retaining ring in one end of the cylinder, a sealing cup seated on the retaining ring, a head on the other end of the cylinder having a concentric extension protruding into the cylinder, said head and extension having an axial bore providing a discharge port for the cylinder, a piston reciprocable in the retaining ring, a chamber ooextensive with the piston receiving the extension on the head of the cylinder, said chamber having ports providing communications between the chamber and the cylinder, means for closing s. id ports during the compression stroke of the piston, means for sealing the chamber carried by the piston and the extension on the head, a spring between the sealing means, an annular head on the piston dividing the cylinder into two annular chambers, said head having openings therethrough providing communications between the annular chambers, a collapsible sealing cup on v the head closing the openings during the return stroke of the piston, and a spring interposed between the cup on the head and the cup on the retaining ring. 4 v

6. A fluid pressure producing device comprising a reservoir, a cylinder supplied therefrom, a retaining ring in one end of the cylinder, a head on the other end of the cylinder having a concentric extension protruding into the cylinder, said head and extension having passages therethrough providing a discharge port for the cylinder, a piston reciprocable in the retaining ring, a chamber co-extensive with the piston receiving the extension on the head of the cylinder, said.

chamber having spaced ports in its bottom and a port adjacent its open end providing communications between the ch'amber and the cylinder, a

inder into two annular chambers, said head having 10 openings therethrough providing communications between theannula'r chambers, a collapsible sealing cup on the head of the piston closing the openings therein during the return stroke of the piston. a sealing cup on the retaining ring, and a spring interposed between the cups.

HERBERT C. BOWEN. 

